Cokeless smelting of ore



Jan. 8, 1963 R. a. ATKINSON ETAL 3,072,474

COKELESS SMELTING OF ORE Filed March 21, 1961 m. TS M CE C US F E o A DA 0 l v 06 O C L L R O A B PL GO N .E m R N VIU N U 0 BF E J F B C I R R A 2 l A N V C CR U 1 1. F I H u m M N w H mm m o m M mm 7 w G M m. I G r) k I W C U D EOP ZOTrU mm "M W 5 3 N N NTmw E 4 L N K 0 2 WL K .ln 3 F S (I ll +ll. J V

24 STORAGE AND /oR TRANSPORTATION SLAG v A T TURNED/.5

United States Patent Ofifice 3,072,474 Patented Jan. 8 1963 3,072,474 COKELESS SMELTING F ORE Robert G. Atkinson and John W. Loy, Bartlesville, Okla, assignors to Phillips Petroleum Company, a corporation of Delaware Filed Mar. 21, 1951, Ser. No. 97,273 3 Claims. (Cl. 75-11) This invention relates to cokeless smelting of ore, for example, iron ore.

In one of its aspects, the invention provides an opera tion or system in which a self-fluxing, self-reducing, and completely fusible mixture of ore and petroleum carbon is prepared by partially reducing the ore employing gases obtained from petroleum treatment, admixing the partially reduced ore with pitch and carbon black also obtained from petroleum treatment, and other ingredients such as lime, and then completely reducing the final admixture, as in an electric smelting furnace In another of its aspects, the invention relates to an operation in which a heavy oil is subjected to vis-breaking, there is obtained from the vis-broken oil a heavy oil and a pitch, the heavy oil is subjected, at least in part, to conditions producing a reducing gas and, at least in part, to conditions producing carbon black, the reducing gas is used to at least partially reduce the ore, the partially-reduced ore is admixed with the pitch, carbon black, and other ingredients, for example, lime, the mixture is briquetted and calcined, following which it is completely reduced by smelting, as in an electric furnace. In a further aspect of the invention, there is provided suitable apparatus comprising, in combination, an oil-conversion unit, a furnace for converting a heavy fraction of oil from said unit to a reducing gas mixture, a furnace for converting an oil from said oil-conversion unit to carbon black, a kiln for reducing iron ore, means for passing reducing gases from the first-mentioned surface to said kiln, a mixing and briquetting or forming unit, means for passing partially reduced ore from said kiln, pitch from said unit, and carbon black from said second-mentioned furnace to said mixing and briquetting unit, a calcining unit, means for passing briquettes from said mixing and briquetting unit to said calcining unit, a smelting furnace, and means for passing calcined briquettes from said calcining unit to said last-mentioned furnace.

In the usual method for the production of iron, a mixture of iron ore, limestone and metallurgical coke is fed to the top of a blast furnace and molten iron and slag are removed from the bottom of the furnace. The metallurgical coke employed is of high strength so as to support the charge without crushing and thus give sufficient porosity to the reaction bed. Such coke is prepared from coal relatively free of sulfur.

In many parts of the world, there are iron ore deposits in promixity to petroleum'fields, but where suitable coal deposits are unavailable. When coke is prepared from avail-able petroleum supplies, it is found to be unacceptable for use in the well-known processes for reducing iron ore because of physical characteristics and sulfur content, unless prohibitively expensive processes are employed.

Processes have been proposed in which reduction of the iron ore is accomplished by the use of natural gas, gaseous decomposition products of heavy petroleum products and oil itself. In general, these processes have proven to be unattractive both technically and economically.

In most prior methods, the steps involved in the prep-* ar-ation of the feed stock up to the final reduction step and the reduction step itself are integral, and there can be no delay between them.

We have now overcome the difliculties experienced heretofore in reducing iron ore with petroleum products, and provide an integrated process requiring only a pctroleum crude, iron ore and lime as material, together with some electrical energy for the final reduction step.

We have now conceived that by vis-breaking an oil, such as a heavy viscous crude oil which contains asphaltic constituents and obtaining pitch and carbon black from at least one of the fractions of the vis-broken crude oil, and converting at least another portion of a fraction of the vis-broken oil to reducing gases, we can partially reduce iron ore and can admix the partially-reducing iron ore with said pitch and carbon black and that we need only add a fiuxing agent such as lime to prepare a briquette suitable for calcining and smelting.

An object of this invention is to provide an integrated system in which cokeless smelting of ore, for example, iron ore, can be accomplished using only a petroleum crude oil, iron ore, and lime to prepare a mixture or briquette suitable for smelting, as in an electric furnace. Another object of the invention is to provide a self-fluxing, self-reducing, and completely fusible mixture of ore, petroleum carbon and lime. A still further object of the invention is to provide an apparatus or system for so converting an oil that conversion products, so obtained, iron ore and lime can be used to prepare a briquette for electric smelting.

Other aspects, objects and the several advantages of this invention are apparent from this disclosure, the drawing and the appended claims.

According to the present invention, a heavy crude oil is vis-broken, producing a pitch fraction and a heavy oil, the heavy oil is converted in a furnace to produce a reducing gas comprising carbon monoxide and hydrogen and a carbon black, iron ore is reduced to Fe or, with the reducing gas, a partially-reduced iron ore thus ob tained is admixed with the carbon black, pitch and lime, in proportions required for reduction of metallic iron in slag, is formed into briquettes, the briquettes are calcined and then subjected to smelting, as in an electric smelting furnace.

Referring now to the drawing, a heavy viscous crude oil, for example, Monagas crude, is passed by one into vis-breaker furnace 2 and by 3 to fractionator 4, wherein the oil stream is fractionated. Light materials formed such as gas, gasoline, and some heavier are taken overhead by 5 for use as will be understood by those skilled in the petroleum refining art. A heavy oil is taken as a sidestream 6, a portion of which passes by 7 into furnace 8, another portion passing by 9 into furnace 10. In furnace 8, the oil is converted in the presence of oxygen supplied at 11 into a reducing gas containing essentially carbon monoxide and hydrogen. This gas is passed by 12 to reducing kiln 13, to which iron ore is fed at 14. Reduced iron ore consisting essentially of FeO and Fe,O-. and SiO is passed by 14 together with pitch from fractionator 4, passed by 15 into mixing and briquetting unit 16 to which fluxing agents, in this case, lime, are added by 17. In furnace 10, the oil is converted in the presence of some air supplied by 18 to carbon black which is passed by 19 to unit 16. Briquettes from unit 16 are passed by 20 to calcining furnace 21 and by 22 to electric smelting furnace 23. If desired, storage can be provided as shown at 24.

It will be understood by one skilled in the art in possession of this disclosure, having studied the same, that the drawing is merely diagrammatic and is intended to merely sufiiciently illustrate the concepts of the invention so that one skilled in the art, having this disclosure before him, can execute the same, applying only routine knowledge and skill. Thus, for example, it is clear that the calcined briquettes from furnace 21 can be conveyed to furnace 23 by way of a chute or other transportation.

J This is indicated and intended to be included in item 24 of the drawing. Naturally, any drawing of this type does not include the manifold details which one skilled in the art will supply when designing a plant particularly suited to his purpose but employing the concepts here laid out and described.

There can be utilized as fuel in the operation, light gaseous products obtained from the vis-breaking or elsewhere in the system.

The conditions for vis-breaking and fractionating the crude oils used in the invention are well known in the art. Usually a temperature in the approximate range 875-1100 F. and a pressure in the range 150-400 psi. will be employed when converting Monagas crude. It will be understood by one skilled in the art that the crude can be subjected first to a topping operation to remove dissolved ga and light liquid components therefrom. If the oil feed stock is high in sulfur, it can first be subjected to a dehydrosulfurization treatment to remove sulfur. Such treatment is within the skill of the petroleum technologist. One of the advantages of this invention is that preliminary desulfurization of a highly sulfur bearing oil is not absolutely essential because the sulfur content of the oil fraction will be converted into hydrogen sulfide and sulfur dioxide in the furnaces. These sulfur bearing gases can be removed from the desirable reducing gases produced by the furnaces at much less cost than the sulfur can be removed from the oil. The methods for such sulfur removal are widely known in industry. Any small amount of sulfur added in the pitch in the briquetting operation will be driven off in the calcining furnace.

Before taking the heavy oil to the furnaces to produce the reducing gas and carbon black, removal of asphaltic materials can be practiced, following which the oil is partially combusted in a furnace of the type utilized in the production of high abrasion furnace black well known in the art of producing carbon black. In one modification, as described in the drawing, the reducing gas can be produced separately in a furnace such as in Patents 2,377,245 and 2,750,434, issued May 29, 1945, and June 12, 1956, respectively, to Joseph C. Krejci. The carbon black can be separately produced as taught in Patents 2,375,798 and 2,616,795, issued respectively May 15,

1945, and November 4, 1952, to Joseph C. Krejci. The off-gases from these furnaces can be used for their sensible heat and fuel values in other parts of the operation, especially in the calcining furnace, and the initial fractionation step. Thus, as a feature of the invention, economy can be practiced by combining the heating values of the off-gases with the fractionation step.

Kiln 13 can be a Herreshoff kiln, or, in lieu of a rotary kiln, a traveling grate unit can be used, the partially reduced iron corresponding to Fe O ,or a mixture of Fe O and FeO.

In unit 16, the partially reduced iron ore, carbon black and pitch, produced as described above, together with lime and, if desired, other fluxing agents, are thoroughly mixed and formed into shapes such as pellets or 'briquettes. To facilitate completion of the reduction reactions to follow, there can be incorporated other agents such as Fe(OH) and FeCO The proportions in which the various materials are balanced to obtain a self-fiuxing, self-reducing, and completely fusible, or otherwise consumed, briquette can be readily determined by one skilled in the art and will depend to an extent upon the precise nature of the substances comingled.

The calcined briquettes can be stored or transported until needed, or they can be passed directly to an electric smelting furnace. The consumption of carbon electrodes will provide a certain amount of reducing agent (carbon) to participate in complete reduction; continuously forming electrodes can be used as an inexpensive way to add carbon to the furnace. Twenty-five hundred pounds of Fe O can be reduced with about 200 or 300 pounds of carbon to produce a ton of semi-steel.

Example gallons of v-is-broken Monagas crude oil is fractionated into about 60 gallons of a liquid product and about 360 pounds of an asphaltic pitch having a softening point of about 300 F. About thirty gallons of oil recovered from the fractionator are fed to a partial combustion furnace (8 in the drawing) reacted with oxygen in the furnace to produce 4500 cubic feet of reducing gas consisting of a mixture of CO and H The additional 30 gallons of oil which are recovered from the fractionator are fed to a tangential burner furnace (10 in the drawing) and there reacted with air to produce pounds of carbon black.

One ton of iron ore containing 1600 pounds of Fe O and 400 pounds of gangue (SiO is fed into kiln 13 in which it is heated to a temperature of 1000 F. by firing a Dutch oven auxiliary to the kiln. In addition to the combustion gases from the Dutch oven, there is passed through the kiln all the reducing gas which exists from furnace 8. The reducing gas which is passed through the kiln reduces the Fe O in the kiln to a mixture of Fe O and FeO. In practice, furnace 8 of the accompanying flow sheet can be constructed as part of the Dutch oven firing system which is used to heat the kiln. Also the gas exiting furnace 10, which is rich in CO and H also can be passed through the kiln to increase the efficiency of the process.

The partially reduced iron ore which exits the kiln along with its gangue (SiO content is mixed with 360 pounds of pitch obtained from the fractionation step and 120 pounds of carbon black obtained from burning oil in the tangential burner. There is also added to this mixture a fiuxing agent consisting of 450 pounds of CaO. All the constituents are intimately mixed and then formed into briquettes with a briquetting machine.

The briquettes are passed through calcining furnace (21 in the drawing) in which they are heated to a temperature of about 2000 F. The firing of the briquettes removes all volatile matter from the pitch, hardens the briquettes, and further reduces the iron ore. After firing, the briquettes can be cooled and placed in storage to give surge capacity to the process or they are transported to the electric furnace and charged into it while still hot. Briquettes which are made up of properly balanced proportions, as described above, can be smelted in an electric furnace in which they will be completely fusible because they are self-fluxing. About eight hundred fifty pounds of molten slag and about 1000 pounds of molten iron is removed from the hearth of the electric smelting furnace, in this example.

From the foregoing describtion, it will be seen that our process is suitable for producing iron from ore, employing only petroleum products as reductants. Furthermore, it is possible to employ petroleum products with relatively high sulfur content. Additionally, it is unnecessary to produce a metallurgical coke from the petroleum products and attempt to reduce the sulfur content thereof, an exceedingly troublesome and expensive process. Because of cost, it is generally desirable to obtain the electrical power required for the smelting furnace from water power, but this too might be generated from petroleum fuels. The process has flexibility, in that the calcined briquettes can be stored for a period of time before smelting, or they can even be transported to a different geographical'location for smelting. The process is ideally suited to operation on small scale, and the requirements of iron ore, petroleum and water power electricity are found in several places in the world where coal and metallurgical coke are not available.

The term Monagas crude employed above refers to crude oil obtained in the State of Monagas, Venezuela, and is chacaterized by a high asphaltic content and high viscosity. Other oils suitable for use in our invention include other petroleum crudes from Venezuela having these same general characteristics, for example Boscan crude. Another reducing agent is the material obtained from Athabascar tar sands from the Athabascar district of Canada. Also, bitumens in general may be employed in our invention.

Various ores that can be reduced with carbon (carbon monoxide) are suitable for our process. Of chief interest are the iron ores taconite, hematite, magnetite, etc. Other ores includes oxidized lead ores, zinc ores, tin ores, copper ores, etc. In some cases, it will be desira'ble to concentrate or beneficiate the ore, or provide other pre-treatments, as understood by those skilled V in the art.

Reasonable variation and modification are possible within the scope of the foregoing disclosure, the drawing, and the appended claims to the invention, the essence of which is that there have been set forth an integrated process and apparatus for the reduction of ore, such as iron ore, the process comprising the production of reducing gas, pitch, and carbon black from the petroleum oil, the partial reduction of the ore with the reducing gas, the admixing of the partially reduced ore with the pitch and carbon black and a fluxing agent, such as lime, and subsequent calcining and smelting to produce, in the case of iron ore, the iron or semi-steel.

We claim:

1. A process for the smelting of iron ore which comprises subjecting a heavy petroleum oil to viscosity breaking, producing a stream of viscosity-broken oil, fractionat ing the stream of viscosity-broken oil to obtain a pitch fraction and a heavy oil fraction; converting a portion of the heavy oil fraction into a reducing gas containing carbon monoxide and hydrogen, and converting at least another portion of said heavy oil to carbon black, sub jecting said ore to reducing conditions in the presence of said reducing gas, admixing the ore thus-treated with said pitch, lime and said carbon black, forming the mix ture thus obtained, calcining the formed mixture and subjecting the formed, calcined mixture to smelting.

2. A process according to claim 1 wherein the smelting is conducted in an electric furnace.

3. A process for the cokeless smelting of iron ore which comprises viscosity breaking a petroleum oil, obtaining from the viscosity broken petroleum oil a reducing gas, pitch, and carbon black, reducing an iron ore, at least in part, by contacting the same under reducing conditions with said reducing gas, admixing the thustreated iron ore with said carbon black, pitch and a fluxing agent, forming the mixture and subjecting the formed mixture to calcining and smelting.

References Cited in the file of this patent UNITED STATES PATENTS Re. 19,770 Brown Dec. 3, 1935 748,739 Huifelmann Jan. 5, 1904 1,116,024 Crusius Nov. 3, 1914 1,303,799 Jarvis May 13, 1919 2,287,663 Brassert June 23, 1942 2,375,797 Krejci May 15, 1945 2,417,949 Riveroll Mar. 25, 1947 2,621,117 Garrison Dec. 9, 1952 2,871,115 Agarwal Jan. 27, 1959 

1. A PROCESS FOR THE SMELTING OF IRON ORE WHICH COMPRISES SUBJECTING A HEAVY PETROLEUM OIL TO VISCOSITY BREAKING, PRODUCING A STREAM OF VISCOSITY-BROKEN OIL TO OBTAIN A PITCH ING THE STREAM OF VISCOSITY-BROKEN OIL TO OBTAIN A PITCH FRACTION AND A HEAVY OIL FRACTION, CONVERTING A PORTION OF THE HEAVY OIL FRACTION INTO A REDUCING GAS CONTAINING CARBON MONOXIDE AND HYDROGEN, AND CONVERTING AT LEAST ANOTHER PORTION OF SAID HEAVY OIL TO CARBON BLACK, SUBJECTING SAID ORE TO REDUCING CONDITIONS IN THE PRRESENCE OF SAID REDUCING GAS, ADMIXING THE ORE THUS-TREATED WITH SAID PITCH, LIME AND SAID CARBON BLACK, FORMING THE MIXTURE THUS OBTAINED, CALCINING THE FORMED MIXTURE AND SUBJECTING THE FORMED, CALCINED MIXTURE TO SMELTING. 